The nose has neural and cellular elements that are in many ways similar to those found in the bronchi. Indeed there is recent interest into nasal responses for the insight they give into bronchial processes. Nevertheless, there may be instances where the two airways respond differently and where, in particular, nasal function might be considered compensatory for bronchial reactivity and obstruction. In studies on anesthetized animals, we will measure tracheal and nasal responses to various stimuli known to affect neural output to airways. Studies will compare changes in nasal vascular and airflow resistance with changes in tracheal tone in response to changing blood gases, simulated exercise, mechanoreceptor stimulation of the airways, and broncho- and naso-contriction and determine how these respiratory reflexes influence the two separate airways. The role of central coordination of bronchial and nasal caliber will be investigated by measuring responses before and after cooling of the ventral medullary surface of the medulla. Studies in healthy human subjects and in patients with lung disease will determine the correlation between nasal and bronchial reactivity in response to pharmacologic, immunologic, and non-immunologic challenges. Nasal function will be assessed using measurements of airflow resistance and examination of washes for cellular and eicosanoid contents. Bronchial function will be assessed using measurements of specific conductance. Studies in patients will determine whether exposing the nose to immunologic and non-immunologic stimuli alters nasal and bronchial responsiveness to subsequent challenges with these and other provocations such as cigarette smoke and exercise. Results will provide new information on the control and coordination of nasal and bronchial patency and on the ability of nasal and bronchial patency and on the ability of nasal function to contribute or adapt to conditions of bronchial hyperreactivity.